Splitting a piece of inorganic material can be accomplished by mechanical equipment and processes, such as wire saw, band saw, and the like. For glass materials, splitting can be effected by mechanical scoring (i.e., forming a scoreline on a surface) followed by bending and splitting. Mechanical scoring requires the removal of part of the bulk or surface material via friction, resulting in the formation of particles. Such particles can contaminate or even damage the surface of the material subject to cutting. Moreover, the edge quality of a glass sheet produced by mechanical scoring and cutting often does not meet the stringent requirements of demanding applications, such as the production of LCD panels.
Laser scoring has been reported as an alternative cutting and scoring technology in lieu of mechanical scoring. A CO2 laser with a wavelength of about 10.6 μm, when irradiated to an absorbing glass material, can cause the temperature of the exposed area to rise. With or without the assistance of a coolant, the tensile stress caused the thermal gradient resulting from the absorption of the irradiation can lead to the direct splitting of a glass sheet, or the formation of a line of defect (“vent”) along which the glass sheet can be split with the assistance of mechanical bending.
Laser scoring process parameters such as speed, laser power, process window, residual stress etc. depend on a number of factors, including thermal characteristics of the glass and laser beam properties—beam shape, size and also its intensity profile.
In the production of large-size LCD panels and many other products utilizing glass substrates, it is highly desired that the as-cut glass substrate has a high edge quality, and can be produced with high speed and efficiency, even as the size of the glass substrate grows larger and large from one generation to the next. This has posed significant challenges to the traditional mechanical and laser scoring technologies alike.
Thus, there is a need of a precision glass cutting technology. The present invention, as an improvement to existing laser scoring technology, answers this and other needs.